We propose to isolate and characterize the etiologic agents of scrapie and transmissible mink encephalopathy (TME); to study the pathogenesis of scrapie and TME in suitable hosts; and to study the etiological and epidemiological interrelationships between the animal and human (Kuru and Creutzfeldt-Jakob Disease) encephalopathies. BIBLIOGRPAHIC REFERENCES: Marsh, R. F.; Sipe, J. C.; Morse, S. S.; and Hanson, R. P. (1976). Transmissible mink encephalopathy: Reduced spongiform degeneration in aged mink of the Chediak-Higashi genotype. Lab. Invest. 34: 492. Semancik, J. S.; Marsh, R. F.,; Geelen, J. L. M. C.; and Hanson, R. P. (1976). Properties of the scrapie agent: Endomembrane complex from hamster brain. J. Virol. (in press).